Semiconductor device technologies continue to evolve, providing higher chip density and operating frequencies. Fin-type field-effect transistors (FinFETs) are one type of transistor technology that is currently used to help provide desired device scaling while maintaining appropriate power consumption budgets.
This fin-type field effect transistor (FinFET) is a transistor that is formed within a fin of material. A fin is a relatively narrow width, relatively tall height structure that protrudes from the top surface of a substrate. The fin width is intentionally kept small to limit the short channel effect. In many FinFet's, a fin cap is positioned on the top of the fin and runs along the fin length. The fin cap has a fin cap width equal to the fin width, and fin cap height that is less than the fin height.
In a conventional FinFET, a gate conductor is positioned on the top surface of the substrate and over a portion of the fin. The gate conductor runs parallel to the top of the substrate and is perpendicular to the fin length such that the gate conductor intersects a portion of the fin. An insulator (e.g., gate oxide) separates the gate conductor from the fin and the fin cap. Further, the region of the fin that is positioned below the gate conductor comprises a semiconductor channel region. The FinFET structure can include multiple fins and fin caps, in which case the gate conductor would wrap around, as well as fill in, the space between these fins.
During FinFET formation, source and drain recesses are formed and typically require additional cleanings to have epitaxial regrowth above the fin at the source and drain regions. Some epitaxial junctions formed by this epitaxial regrowth are stressed. During manufacture, it is difficult to make a uniform fin recess dimension when multiple fins are used and epitaxial junctions are stressed. Also, during manufacture, the fin profile is often rounded and the fin surface is damaged by aggressive reactive ion etching (RIE) after spacer formation, and during in-situ doped epitaxy. These factors may impact adversely transistor functionality.